I have a tetra whisper heater. I am yet to see my tank dip below 75 degrees and my pleco loves my heater. Most of the time the tank is at 80 to 85 degrees. I would say that this is a reasonably good heater. I am happy with it.

I have high wattage VHO lighting that puts out conciderable heat and I suspected you might have the same thing happening. As long as the heater keeps the water temp from dropping below 75* everything is fine.

I have seen cases where the hobbiest depended on the heat from the lights to warm the tank. When the lights were off and the room temp was lower than usual, the fish would be stressed by the temp drop.

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